Agricultural crops suffer losses due to diseases and pests. Chemical and biological insecticides have been in use for a long time to minimize yield losses due to insect pests. Traditionally, these are externally applied as formulations on crops. The most common biological pesticides used include Cry proteins from Bacillus thuringiensis (Bt), which is a soil bacterium. Bt has a vast collection of cry genes. The encoded proteins vary widely with respect to their insect control efficacy and target insect specificity. It produces crystalline inclusions containing these proteins during sporulation. When ingested by insect larvae, these crystalline inclusions dissociate into monomers in the alkaline insect gut. The monomers further undergo proteolytic cleavage which results in an activated insecticidal protein. This protein binds to the larval gut lining and damages it inducing an antifeeding behavior in the larvae and eventually death. The cry protein binds to the larval gut lining at specific host-encoded receptors. One of the first genes to be commercially exploited for trait development in crops is the Bt cry. This was the advent of plant produced pesticides. A few genes like cry1Ac, cry1F, cry2Ab, have been effectively incorporated into plants for control of insect pests.Bt Cotton

Bt cry1C Highlights

Cry1Ca1 – 630 amino acid residues

The active toxin alone has been expressed

Cry1Ca1 has effective control of Spodoptera litura

Cry1Ca1 has an alternative mode of action for control of Helicoverpa

The gene is completely codon optimized for cotton

Event ID: The selected cotton event for further evaluations is MLS9124

Metahelix has developed two versions of Bt cotton with proprietary cry1C (Spodoptera control) and cry1Ac (Bollworm control) based genes. The combination of cry1C and cry1Ac is also being developed as a stack. The Bt Cotton expressing cry1C is currently at the stage of regulatory approvals for Large Scale Trials (LST) for agronomic and trait evaluation. The biosafety studies for the Cry1C protein have been completed and the event MLS9124 is found to be safe.

Metahelix candidate genes cry1Ac and cry1C have different modes of action on bollworms. While cry1Ac has no activity against Spodoptera litura, cry1C is highly effective in its control. These two genes were chosen for controlling the bollworms and Spodoptera litura and also delay resistance development among the bollworm populations.